- SS-HQ1 Application Notes -
Ver.1.0.0 January 7, 2005
57
9. RS-232C Communication and Communication with
Peripheral ICs
9.1. RS-232C Communication
9.1.1. Interface
The SS-HQ1 system supports the RS-232C format (half duplex mode) as a means of communication with
external PCs. However, RS-232C communication requires an external IC for converting the 3.3V logic to the
RS-232C level (recommended product: MAX3232, made by Maxim), as well as pin settings. Please see the
application circuit we have provided for information on the connections with the MAX3232 and the RS-232C
connector (D-sub 9 pin).
In cases where the SS-HQ1 system is controlled through an external microcomputer, we recommend using
that because it includes serial communication specifications which are more efficient than RS-232C. For
details, see “12.4 When Using the External Microcomputer”.
Use the pin settings in the following table on a CXD3172AR which is to be used in RS-232C.
If you switch SIFSEL, be sure to reset the system.
Table 9.1-1 Pin Settings for Communication
Signal name
Pin No
I / O
Description
XCS(XCTS) 15 IN
Always
High
SI(RXD)
16
IN
Serial settings data input
SO(TXD)
17
OUT
Serial settings data output
SCK(XRTS)
18
OUT
Pull Up ( Resistance of 100k ohm)
*1
SIFSEL 13 IN
Always
High
*1
Because 18pin becomes an input terminal by SIFSEL=L, it uses it with Pull up as a floating measures.
18pin becomes L output by SIFSEL=H.